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ax25: fix info leak via msg_name in ax25_recvmsg()

When msg_namelen is non-zero the sockaddr info gets filled out, as
requested, but the code fails to initialize the padding bytes of struct
sockaddr_ax25 inserted by the compiler for alignment. Additionally the
msg_namelen value is updated to sizeof(struct full_sockaddr_ax25) but is
not always filled up to this size.

Both issues lead to the fact that the code will leak uninitialized
kernel stack bytes in net/socket.c.

Fix both issues by initializing the memory with memset(0).

Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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1 parent 9b3e617 commit ef3313e84acbf349caecae942ab3ab731471f1a1 @minipli minipli committed with davem330 Apr 7, 2013
Showing with 1 addition and 0 deletions.
  1. +1 −0 net/ax25/af_ax25.c
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@@ -1642,6 +1642,7 @@ static int ax25_recvmsg(struct kiocb *iocb, struct socket *sock,
ax25_address src;
const unsigned char *mac = skb_mac_header(skb);
+ memset(sax, 0, sizeof(struct full_sockaddr_ax25));
ax25_addr_parse(mac + 1, skb->data - mac - 1, &src, NULL,
&digi, NULL, NULL);
sax->sax25_family = AF_AX25;

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